the most likely 800 kit is just the aftermarket Wisesco pistons and remachined heads, very common, in general this kit ran smoother than stock and in many cases owners claimed better clutch life. The later style cat clutch's with the small taper will work ( M5 or ). No great big power boost with the kit, typical overbore kit where stock transfer ports were handling all they could so a bigger piston didn't really produce more power or significant seat of the pants power. Pistons still show in Wiseco's catalogue.
the Yam primary worked good on these.......expensive but easy to rebuilt on the sled and keep the rattling down.
I've seen many 790 Wiseco BB's in later year 700's and power was negligible. The electrical, set to run with that ****ty single pipe just did not produce the power we remembered when the 700 first came out.
My '94 with a 790 and extensive porting handles all other 790's and the 890 Bigger bore with ease on the hills. But most are drop in kits while, like I said, I have a not so stock motor. However do not kid yourself, 160hp is not realistic from the drop in kit like was advertised 10 years ago.
As far as cltch and crank issues, went 10,000 miles on original crank before rod bearing let loose. 6,000 on the BB. Run a Comet 4-Pro balanced and idle high. She runs at 8400RM with the PSI ModBlasters.
Comparison:
Head to head with my '06 SLP'd 800 REV 162x2.5 CE(Advertised 163hp?)
vs
'04 KR Special 150x2.5 CE
In bottomless pow the Cat moves mucch faster than the Doo, trackspeed and groundspeed is way better, but the 162 on the Doo kept the marks on the hill pretty even. If I had more track the Cat would easily outclimb my Doo. In comparison sake, my '06 runs a dead even race against a clutched 2010 800 163.
I love the sled and the motor.
